In blender or food processor with the steel chopping blade in place, puree the berries, strain, and discard the seeds. Set puree aside. In glass measuring cup, sprinkle gelatin over water. Let stand 1 minute to cause the gelatin to absorb the water. Then microwave on high for 30-40 seconds to melt the gelatin. Stir in the sugar, milk, pureed berries, yogurt, and chocolate or dried fruit. Freeze according to the manufacturer's directions. Makes about 1 quart.